Apparatus allowing the optician to determine these parameters already exist and generally comprise a housing defining, on the one hand, at one of its ends, a target aperture intended to receive the spectacles worn by the patient and his corresponding facial portion, as well as, on the other hand, at the opposite end, an ocular aperture provided with an eye-piece aligned on the target aperture and intended to allow the optician to observe the ophthalmic lenses and the patient's eyes while, in the housing, a lens is placed between the two apertures, the optical axis of which coincides with that of the eye-piece, and a light source disposed outside the optical axis of the said lens is disposed so as to emit a luminous beam towards the said lens and the target aperture, in the direction of the said optical axis, optical reflecting means allowing the optician to receive through the said eye-piece frontal and lateral images of the ophthalmic lenses superimposed upon the patient's eyes, as well as optical marking and measuring means are interposed on the path of the luminous rays between the target aperture and the eye-piece in such a manner that their images are visible to the optician at the same time as the above-mentioned images.
An apparatus of this type is in particular disclosed in German Pat. No. 1 060 622. This known device utilizes as optical reflecting means, for each of the patient's eyes, two prisms that send back the lateral image (i.e. the image of the profile) of the cornea, associated to the image of an adjusting mark provided on one of the prisms, towards the ocular aperture where it is superimposed on the frontal image of the cornea--thus of the pupil--that is transmitted towards the ocular aperture without optical reflection, but with the interposition, on the optical path, of reference marks, such as lines or cross-hairlines. This arrangement is supposed to allow the optician, through the lateral images of the two corneas and the associated reference marks to prevent any angular shift of the device in the horizontal plane, with reference to the correct symmetrical position with respect to the patient, in which the image of each of the said adjusting marks must be at a tangent to the apex of the cornea involved.
The known device is not designed for the appreciation, by the optician, of the distance separating the spectacle lenses from the corresponding pupils of the patient, nor for measuring the "mounting height" of the lenses, i.e. the distance between each pupil and the lower edge of the associated lens. Without doubt it allows measurement of the distance between the pupils, or their "half-distance" avoiding measuring errors due to an angular shift of the device with respect to the eyes of the patient, but this result--which in itself is already limited--requires a relatively complex handling on the part of the optician, who is in fact limited by the basic conception of the device, to adjust it in depth with respect to the patient, which constitutes a time-consuming operation. Furthermore, in the disposition of a device such as that disclosed in the above-mentioned German patent, the optical path of the lateral images of the corneas passes through the central zone of the lens and is deflected prior to reaching this zone. Due to this fact, the lens must be placed at a relatively great distance from the patient's eyes, which comprises a risk of parallax is errors resulting in turn, in measuring errors. Another drawbacks of the known device lies in the fact that due to the "cranked" plotting of the optical path of the lateral images of the corneas, in front of the lens, these images are at the level of the ocular aperture, therefore, for the optician, shifted in depth with respect to the frontal images of the corneas and the pupils. This comprises for the optician the necessity of accomodating in order to see at the same time the two images in a clear manner. Then it is well known that such an accomodation induces a substantial and undesirable fatigue.
In another device, disclosed in French Pat. No. 1 506 352, the optician sees through the lens the image of the patient's eyes, and by displacing the reference marks in order to cause them to coincide with the reflection supplied by the corneas or "corneal reflection", he can measure the pupillar "half-spacing" of the patient. Using another set of reference marks, arranged perpendicularly to the first, the optician can set a reference line in a tangent position with respect to the lower edge of the spectacles lens or its rim or eye-wire and consequently determine the "mounting height". He can, furthermore, also measure the distance between the patient's eye and the associated spectacles lens, by placing the device laterally with respect to the associated spectacles frame.
While allowing to measure all the required lens mounting parameters, this prior device involves for the optician a plurality of steps in handling said device, as well as an ascertained habit of measuring there with, since this device has to be displaced and replaced several times with respect to the spectacle-wearing patient.
The aim of the present invention is to provide a device of the type defined herein-above that does not present the drawbacks of the known devices, which allows to measure all the parameters required for mounting lenses on spectacle frames by simple operations, without complicated handling of the device, which reduces to a minimum the visual accomodation required by the optician and supplies accurate measuring results, free of parallax is or other errors and the dimension and cost of which are reduced.
With this purpose in view, the invention provides an apparatus for measuring the ocular parameters of a patient, especially the parameters required for mounting ophthalmic lenses on a spectacle frame with a view to adaptating the same to the needs of the patient, comprising a housing defining, at one of its ends, a target aperture intended to receive the rims or eye wires and lenses of the spectacle worn by the patient, and at the opposite end, an ocular aperture aligned with said target aperture and provided with an eye-piece intented to be observed by an operator, the said housing containing a light source adapted to emit a luminous beam towards the said target aperture, a bi-convex lens or a Fresnel lens interposed between the said target aperture and the eye-piece so that its optical axis coincides with that of the eye-piece and so that the said lens forms for the operator, in association with the eye-piece, frontal and lateral images of the lenses and lens-rims of the spectacle frame, as well as the eyes of the patient, reference marking means that are adapted to be adjusted with respect to the patient's eyes and the image of which is intended to be observed through the said eye-piece, simultaneously with the said frontal and lateral images, wherein the said reference marking means comprise two pupil spacing reference marks each disposed on a transparent portion of a spacing reference mark holder displaceable independently from the other horizontally and perpendicularly to the above-mentioned optical axis, through a manually actuated control mechanism by using a spacing adjustment member accessible from the outside of the housing, the said reference marking means furthermore comprising two pairs of height reference marks associated respectively to the two eyes of the patient, each height reference mark being disposed on a transparent portion of a vertical height reference mark holder displaceable independently from the others, the said reference marking means comprising furthermore two distance reference marks each associated to a lateral mirror placed laterally with respect to the patient's eye, in a vertical plane inclined substantially at 45.degree. with respect to the optical axis in such a way as to receive the profile image of this eye, of the ophthalmic lens and of the associated spectacle rim and to send it back to a first deflecting mirror placed in a vertical plane perpendicular to that of the lateral mirror and transmitting said profile image toward the optical axis to a second deflecting mirror placed adjacent to said axis in a vertical plane substantially inclined at 45.degree. with respect to that of the first deflecting mirror, in such a way as to transmit said profile image towards the eye-piece, and wherein the said device comprises measuring means for evaluating the position of said reference marks with respect to the eyes of the patient, to the said ophthalmic lenses and to the said spectacle frame, and for visualizing the results of this evaluation.
In one embodiment, the control mechanism of each of the two pupil spacing reference mark holders comprises a rectilinear rack extending transversally to the optical axis and meshing with a pinion integral with a spacing adjustment knob and coaxial to it, the said knob being mounted for rotation about a vertical axis orthogonal to the optical axis, and partially projecting from that wall of the housing which is located opposite in the target aperture, said rack being integral with one of the ends of a cranked rod that bears on its other end the associated spacing marking holder.
According to one advantageous feature of this device the control mechanism of each of the four height reference marking holders comprises a control rod mounted through hinge means, at a location between its two ends, on a vertical and longitudinal wall of the housing, so as to be displaceable in a vertical plane parallel to said optical axis, and bearing at one of its ends, the corresponding height reference mark holders, while the said hinge means comprise a guiding stud laterally disposed on the control rod and slidably engaging in a curved guiding channel or groove provided in the said internal wall, and a curved rack meshing with a pinion integral with a height adjustment knob and coaxial to it, the arrangement being such that each reference mark holder is displaced, along a substantially rectilinear vertical path.
According to another feature of the device, the two pupil spacing reference mark are associated to a spacing scale allowing to measure the horizontal distance between these reference marks and the horizontal distance between the vertical median nasal plane of the patient and each of the said spacing reference marks, the said spacing scale being disposed in a fixed transparent plate mounted in the housing between the target aperture and the spacing and height reference mark holders, where each pair of height reference mark holders is associated to a height scale allowing to measure the vertical distance between the two respective reference mark holders of each pair thereof, the said height scale being disposed on a portion of the lower height reference mark holder of each pair which covers at least partially the associated upper height reference mark holder, while the distance reference marks are each associated to a distance scale disposed on the associated lateral mirror and allowing to measure, in the image received by the eye-piece, the distance between the patient's cornea and the associated distance reference mark.
In a particularly advantageous embodiment, the control mechanisms of the pupil spacing reference mark holders and the height reference mark holders are associated to electric and electronic means adapted to detect the distances between matching reference marks, to produce electric signals representating these distances, to transform these electric signals into digital signals and to use them to display in digital form the said distances by using display windows disposed on the walls of the housing.
Preferably, the two adjustment knobs of the control mechanisms of each pair of height reference mark holders are kinetically connected respectively to the slider and to the resistor of a rotary potentiometer the terminals of which are connected to at least one input terminal of the electronic means of which at least one output terminal is connected to one of said windows for displaying the effective resistance of the potentiometer determined by the relative angular position of the two above-mentioned knobs and representing the vertical distance between the two height reference marks concerned.
According to another advantageous aspect of the present invention, each spacing adjustment knob is kinetically connected to the slider of a potentiometer the terminals of which are connected to the input terminals of the said electronic means of which at least one output terminal is connected to at least one of the said windows for digitally displaying the value of the effective resistance of the potentiometer determined by the angular position of the adjustment knob concerned.
In a preferred embodiment, the said light source is a light source constituted by four punctual diodes disposed at the four corners of a square so as to not to be visible directly by the eye of the operator, the centre of the square being on the optical axis of the eye-piece.
In another embodiment, the above-mentioned lateral mirrors are semi-transparent mirrors that are each provided with an adjustment mark and behind each of which is disposed a plate provided with a distance scale, so that the said eye-piece receives, for each of the patient's eyes, simultaneously the profile image of the eye, the profile image of the eye-wire concerned, the image of the reference mark line and the image of the said distance scale.
In this embodiment, at least one of the semi-transparent lateral mirrors is advantageously pivotally mounted around an orthogonal axis of the said optical axis, so that in the image received in the eye-piece the suitably oriented reference mark of this semi-transparent lateral mirror can be brought through pivoting to be substantially superimposed upon the profile of the rim, while the angle of this pivoting represents the inclination of the said rim.
In a variant, the light source is shifted with respect to the said optical axis and the light beam is sent towards the target aperture through a semi-transparent mirror inclined with respect to this axis and interposed on it between the said target aperture and the said eyepiece, towards which it allows to pass the reflected images of the spectacles and the eyes of the patient, as well as the images of the concerned reference means.